A good friend has been acting strange lately, and she doesn’t look well, either. I’m worried about her, but is it out of line to say something?

Absolutely not. Changes in behavior and appearance can be warning signs of a serious problem. Try saying, “I don’t want to alarm you, but I’ve noticed a change in your personality” or “You seem tired. Do you feel OK?” “Illness saps your energy,” says Kate Strooband, an obstetrics nurse in Eugene, Oregon. Your friend may not even be aware that she is more run-down than usual. Or you may be telling her something she already knows, and your concern may get her to finally see a doctor about the problem, says Susan Halpern, a social worker and psychotherapist and the author of The Etiquette of Illness (Bloomsbury, $12.50, www.amazon.com).